1. Technical Field
The present disclosure relates to a method of manufacturing a semiconductor light emitting element.
2. Description of the Related Art
Light emitting elements employing a nitride semiconductor have a wide band gap that allows the light emitting elements to emit light in the near-ultraviolet to red range, thus, various kinds of studies have been conducted. A typical basic structure of a nitride semiconductor light emitting element includes a stacked-layer structure of an n-type semiconductor layer, an active layer, and a p-type semiconductor layer that are stacked on a substrate, and an electrode is disposed on the p-type semiconductor layer and on a portion of the n-type semiconductor layer that is partially exposed by partially removing the p-type semiconductor layer and the active layer. Studies have been conducted on a structure of a semiconductor light emitting element; particularly, with an aim to obtain higher output, various structures for semiconductor light emitting elements and for electrodes have been proposed.
Semiconductor light emitting elements suitable for face-up type mounting, in which the side having the semiconductor stacked layer serves as the light extracting side, generally include a configuration in which a light-transmissive electrode is formed on approximately a whole upper surface of the p-type semiconductor layer by using a light-transmissive electrically conductive material such as indium tin oxide (ITO), and a p-side pad electrode is disposed on a portion of the light-transmissive electrode. In order to improve current diffusion to the p-type semiconductor layer, a metal material that has a smaller electric resistance is used to form an extending portion which is extended from an external connection portion of the p-side pad electrode onto a wide area of the light-transmissive electrode. For semiconductor light emitting elements having such a structure, for example, as proposed in JP 2008-192710A, in order to reduce optical absorption by the light-transmissive electrode (whole surface electrode) and the p-side pad electrode, a semiconductor light emitting element structure in which an insulating layer made of SiO2 or the like that has a refractive index lower than that of the light-transmissive electrode is provided in the region under the p-side electrode and between the light-transmissive electrode and the p-type semiconductor layer.
For example, JP 2010-62425A proposes that, in order to reduce optical absorption by the bonding layer made of Au or the like in a pad electrode, an electrode structure in which a metal reflecting layer made of Ag, Al, or the like, having high light-reflecting properties, is provided at a lower surface side of the bonding layer.
Meanwhile, the surfaces of the semiconductor light emitting element may be covered with a protective layer made of a light-transmissive insulating material, except for the upper surfaces of the pad electrodes, which are to serve as external connection parts. A number of manufacturing steps are required in production of semiconductor light emitting elements, and reduction of the number of manufacturing steps has been expected. In order to comply with such a demand, a manufacturing method for simplifying manufacturing steps of semiconductor light emitting elements is disclosed, for example, in JP 2012-238823. According to JP 2012-238823, a patterned protective layer is formed in a manner that the entire surface of the semiconductor light emitting element, inclusive of the light-transmissive electrode (whole surface electrode), is covered with a protective layer; a resist pattern defining openings at regions to provide pad electrodes is formed by using a photolithography method; and the protective layer in the openings of the resist pattern is removed by etching. Next, metal layers to serve as the pad electrodes are formed. Then, the resist pattern is removed. Thus, the metal layers are patterned. Accordingly, the pad electrodes are formed. With the method described above, the resist pattern can be shared for forming the protective layer and for forming the metal layer, and accordingly, the manufacturing steps can be simplified.